Lesson video

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Hello mathematicians.

It's me and a very silly Hedwig who's turned her head around again, back for some more maths.

Now, we're very excited because it's another really challenging lesson, but don't worry, we'll work on it together and we're going to split it over two lessons.

So we'll start it today and then the next lesson we'll carry on practising.

So let's find out what we're going to do.

We are going to use the make 10 strategy.

Make 10, to subtract a one-digit number from a teen number.

One of the teen numbers like 13, 14, 15, that kind of thing.

You're going to learn about the make 10 strategy in the context of subtraction and then we're going to apply, we're going to use that make 10 strategy to solve subtraction equations and then you'll do your independent task and you'll do the quiz on the next session, not on this one.

You're going to need a pencil and some paper.

Let's go through our star words, get your hands ready, hands up, star words, make 10, partition, subtract.

Let's see how many times those words pop up in today's lesson.

It's those elves again, with all their presents.

Let's see what they're up to now, shall we? First, there were 14 presents wrapped up, then a child unwrapped six of them.

Do you think they waited until they were allowed to, or do you think they sneaked into the store room? How many presents are still wrapped up now? So there were 14 presents and then a child unwrapped six of them.

How many presents are still wrapped up now? So we know that we're taking away some of those presents that were unwrapped.

So the operation we're doing today is subtraction.

Everybody show me subjection on your hands, well done.

Now we could pick them all off on a number line.

We could go through them crossing them off to try and work out how to subtract six from 14, but that takes quite a long time and it means that we could possibly make lots of mistakes.

So we're going to learn a strategy, the make 10 strategy to be able to subtract them a lot quicker and with hopefully fewer mistakes.

So first there were 14 presents.

Then a child unwrapped six of them.

How many presents are still wrapped up now? So I've got 14 presents in my first box.

First, there were 14 presents, then a child unwrapped six of them.

There's the six presents in the box showing that they've unwrapped six.

Now, how many are there? We are going to make 10, everybody show me make 10.

Make 10.

Now how on Earth and we going to make 10? What is this make 10 strategy with subtraction? Well, I know that if I do 14 takeaway four, ooh, 14 and four, both have the same number of ones.

So 14 subtract four is equal to 10.

So I've made 10.

And right then think about doing fourteen subtract three.

Well, if I know fourteen subtract four is equal to 10, then I know that 14 subtract three, must be 11 because one less than four is three.

But let's try that with our puzzle, with our mathematical problem.

We've got the equation 14 take away six because the elves had 14 presents and then a child came along and unwrapped six of them.

So what we're going to do is to make 10.

The way we make 10 is to partition, ooh, partition.

We learned about that word before.

Partition means to break down, to split apart, to part-ition, cut it into parts.

So we can partition a number to be able to make 10.

Like this, 14 takeaway four, is equal to 10.

Now we just talked about that because 14 has four ones and four has four ones.

So if I take the four ones away, I'm left with 10.

If I know that 14 subtract four is equal to 10, then I can make 10.

There's my four, I put a circle around the four presents that I want to take from there to help me make the 10.

Now I can see that there are still two presents left.

So that six, the six presents in that box, I have partitioned them, I have broken them into the number four and into the number two, to make 10.

I can then subtract those two extra presents to find the answer.

10 subtract two is equal to eight.

So 14 subtract six is equal to eight.

Ooh, that was tricky.

Let's have a look at that on a whole part model.

So we've got six presents that I want to partition.

The six presents to help me make 10.

I've got four in one part and two in the other part.

The four helped me make 10, the make 10 strategy.

And then I just needed to remember to subtract the remaining two.

Fourteen subtract seven.

Hmm, let's try this one now.

So I've got 14 presents and this time we've unwrapped seven of them.

Do you think it was the same child unwrapping all those presents? So I now need to make 10.

Hmm, what could I do to make 10? 14 subtract 14 subtract four.

Just like before, 14 subtract four is equal to 10.

So I will partition the number seven to take that four, to enable me to make 10.

I've put a circle around the four that I want to steal.

How many presents are still in that box? There are three.

14 subtract four is equal to 10.

10 takeaway three is equal to seven.

So 14 takeaway seven, is equal to seven.

14 subtract four is equal to 10.

10 takeaway those left over three is seven.

So 14 takeaway seven is equal to seven.

Let's look at that on the bond there.

I had seven presents and I needed to use four of them to make a bond to 10.

There were three leftover.

We are doing really well with this and it's pretty tricky isn't it? Shall we try it again? We'll use exactly the same process, but we'll do it with the number eight this time, so you can really get into your head what we're doing.

So we've got these elves and they wrapped 14 presents, but then, eight of them fell off the sleigh.

How many presents were there left on the sleigh? I hope it wasn't any of our presents that fell off.

So I've got 14 presents in the first box.

I need to subtract eight.

What's the first thing I need to do? I need to make 10.

How should I make 10? I know that 14 take away four is equal to 10.

But where have I got the four from? Here, I can take that four, to help me make 10.

Now how many are left in that box? One, two, three, four.

There are four left in that box.

14 takeaway four is equal to 10.

10 take away the remaining four is equal to six.

So 14 takeaway eight is equal to six and there's my parts.

The eight presents I've partitioned them into four and four.

Four helped me make the number bond to 10 and then the remaining four, I subtracted.

What about 14 subtract nine? Let's do this on a tens frame so that you can really see the group of 10 that we've made.

I know that 14 take away four is equal to 10.

So I'm going to partition the number nine.

How will I partition the number nine? Hmm, well, 14 take away four.

There's my 14 takeaway four, oh, look, I'll put a circle around that four.

I've got a 10 in the 10's frame, 14 takeaway four.

So I'm going to take the nine presents that I needed to subtract and partition them.

I'll partition them into a four, because I need the four to make the number bond and the presents that are left over are five.

10 subtract five is equal to five.

So 14 subtract nine is equal to five.

Who found that a bit tricky, I did.

Hedwig, did you find that tricky? I think she did, I definitely do, but don't worry, for your independent task, you're not going to do that today.

We just went over it and we'll practise again on next session.

What I would like you to do for your independent task is to have a look at these expressions and figure out which ones have a value of less than 10.

And how do you know? So thinking about that partitioning, 13 subtract seven.

Hmm, will I go below 10, if I take away seven? Yes, because I can see that the number seven is greater than the number three.

So I would need to partition.

The next one, hmm.

17 takeaway eight, have a little think.

Could you take away the eight from the seven or do you need to partition? Put a circle around, or tick the ones, or write down the ones that you think will have a value of less than 10.

And then we'll go through the answers when you come back.

Pause the video now and have a go.

Let's see how we got on.

These are the expressions that have a value of less than 10.

And so we would need to partition them.

Thirteen takeaway seven, I've only got three ones there and I've got seven ones to take away.

So I would need to partition it to be able to subtract.

The same with 17 takeaway eight and 15 takeaway six.

But the other expressions, 17 takeaway three, I could easily do seven takeaway three.

I don't need to do any partitioning there.

18 takeaway seven, again, I've got eight ones and seven ones.

So I don't need to partition, and 16 take takeaway five.

I've got six ones and five ones, so I don't need to partition.

You did fantastically well today, everybody.

It was a really, really challenging lesson, but don't worry.

We're going to go over it again tomorrow or on the next lesson and we'll recap.

Shall we wake up Hedwig and tell her all about what we've just learned? Now, Hedwig, this was a really challenging lesson for us.

We were trying to figure out how we could do some subtraction equations without just doing it on our fingers.

And we use the make 10 strategy.

So that we were able to use the make 10 strategy, we partitioned, we broke apart a number to be able to make 10 and then we subtracted the remaining amount.

Do you think you understand that Hedwig? I think she still wants some practise with it, but she seems pretty confident with what we learned today.

Hopefully you are too.

Really well done today everybody, I'll see you again very, very soon.